A constant voltage circuit with very low impedance is desired in many applications in integrated circuit design. This requirement may include a fast response time and a simple implementation. Thus, an externally supplied voltage source can be regulated to provide an internal power supply for low power, low voltage application. Heretofore, although voltage regulating circuits are well known in the art, they have not satisfied the criteria of supplying low power, with fast response time and simple implementation for use in an integrated circuit.